Add SettingsTab, StatusTab, DataTab and wire up DeviceController

- SettingsTab: chamber ID, master CSV mapping (families A-Z), wafer
  behavior toggle, light/dark mode toggle, Edit CSV Metadata dialog
- StatusTab: connection status card, wafer info, activity log (blank
  until Detect Wafer fires from the side rail)
- DataTab: empty state, ready for parsed data
- HomePage: side rail buttons dispatch device actions and jump to
  Status tab; selectedSideActionIndex defaults to -1 on startup
- DeviceController registered as QML context property in main.py
- LocalSettings: added status persistence fields
- Theme: added subheadingColor and disabledText
- Added serialcomm/ package and backend data/graph modules
- gitignore: restore clean version

pyproject.toml

@@ -1,8 +1,16 @@
 # ===== Project Metadata =====
 [project]
-name = "PySide QtQuick Project"
+name = "pygui"
+version = "0.1.0"
+
+[project.optional-dependencies]
+dev = ["pytest"]
 
 # ===== PySide Build Inputs =====
 [tool.pyside6-project]
-files = ["ISC/HomePage.qml", "ISC/Main.qml", "ISC/Tabs/SelectFileDialog.qml", "ISC/Tabs/SettingsTab.qml", "ISC/Tabs/qmldir", "ISC/Theme.qml", "ISC/qmldir", "backend/file_browser.py", "backend/local_settings.py", "backend/local_settings_model.py", "main.py"]
-∑
+files = ["ISC/HomePage.qml", "ISC/Main.qml", "ISC/Tabs/DataTab.qml", "ISC/Tabs/GraphTab.qml", "ISC/Tabs/SelectFileDialog.qml", "ISC/Tabs/SettingsTab.qml", "ISC/Tabs/StatusTab.qml", "ISC/Tabs/qmldir", "ISC/Theme.qml", "ISC/qmldir", "backend/data_model.py", "backend/device_controller.py", "backend/graph_view.py", "backend/file_browser.py", "backend/local_settings.py", "backend/local_settings_model.py", "main.py", "serialcomm/__init__.py", "serialcomm/data_parser.py", "serialcomm/serial_port.py", "serialcomm/device_service.py"]
+
+[dependency-groups]
+dev = [
+    "pytest>=9.0.3",
+]